Boris Johnson has issued a last ditch appeal in his battle to prevent a third runway being built at Heathrow, insisting it would be "barbarically contemptuous" of local residents.

The Mayor of London, who has long championed the construction of a new hub airport dubbed "Boris Island" in the Thames Estuary, spoke out as the Airports Commission prepared to give its verdict on the idea - expected on Tuesday.

Commission chairman Sir Howard Davies said the body would take a look at the proposal after it was left out of his initial shortlist which contained only the options of expansion at both Heathrow and Gatwick.

Writing in his Daily Telegraph column, Mr Johnson described any backing for Heathrow, in west London, as "madness".

"What frustrates me is that third runway (at Heathrow) is so desperately short-sighted," he added.

There is significant opposition to Heathrow's expansion

"You could not conceivably get it built before 2029, by the airport's own admission - and as soon as it opened it would be full".

Mr Johnson, who plans to stand as the Conservative candidate for Uxbridge and South Ruislip in the 2015 General Election, argued Heathrow expansion would lead to medical problems associated with pollution, as well as congestion on the road network, in the constituency.

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Gallery: Heathrow And Gatwick Fight For The Future (May 2014)

The new transport link hub proposed for Gatwick.

However, he dropped his plan to close Heathrow under his Thames Estuary proposal, saying it could continue to operate as a secondary airport alongside a four-runway "Boris Island" hub.

He argued the UK stood to lose its position as a "great trading nation" as the business lobby group the CBI demanded "spades in the ground by 2020".

Its report, which declined to name a preferred candidate to offer the extra airport capacity, said that having a single UK hub airport with spare capacity to add new routes was critical to the UK's long-term sustainable growth.

Its deputy director-general Katja Hall said: "UK business wants action. There can be no more excuses - we need to see the Airports Commission deliver a strong case for new capacity and a clear schedule for delivery, and politicians to commit to spades in the ground by the end of the next Parliament.

"With Heathrow full and the UK slipping behind in the race for new connectivity, it is essential that the Airports Commission delivers a solution that addresses the ticking time bomb of our lack of spare hub capacity."

The biggest obstacle to "Boris Island" is the estimated cost of more than £50bn while expanding Heathrow to become a three-runway airport and Gatwick to two-runways is priced around £15bn and £10bn respectively.